The present invention relates to aircraft landing gear struts, and in particular to aircraft landing gear struts each having relatively displaceable cylinders and with an orifice formed therein. The loads imposed on the struts causing the noted relative displacement of the cylinders is translated into kinetic energy which is absorbed by a fluid medium contained in at least one of the cylinders and flowing through the orifice in the piston.
In shock absorbing struts of this type, the pressure drop of the fluid medium across the orifice is a function of the flow rate through the orifice so that the orifice is sensitive to the rate of flow, and the flow is directly related to the rate of closure of the strut, and therefore to the sink velocity of the aircraft. Thus, orifices are designed to attenuate the load level to a certain design condition which is compatible with the aircraft's structural thresholds up to a design vertical sink speed. Should the sink velocity exceed the design condition, such as can occur during a heavy landing or crash, the loads transmitted to the aircraft would rise rapidly and cause the structure to fail before the shock strut had fully stroked, and thus very little energy due to the impact would have been absorbed by the landing gear.
It would, therefore, be desirable to have an aircraft landing gear strut which would stroke its full amount and thereby absorb a maximum amount of energy whenever a condition in excess of the design condition is encountered.